“Chaos Theory” is a film in which a man has a profound change of heart and begins leaving all of his decisions in life up to the whims of fate by writing down his various options for any given situation on index cards and selecting one at random to follow. The problem is that it often feels as if the screenplay was written using the same approach. The result is a mess of clashing tones that jerks uneasily from comedy to drama to pathos without demonstrating a particular facility for any one of them.

Ryan Reynolds stars as Frank Allen, an efficiency expert whose patented methods for effective time management have made him a best-selling self-help author and a motivational speaker who delivers the kind of lectures that your boss sends you in the corporate equivalent of a grade-school field trip–you don’t really learn anything (his big innovation is to have you write out everything you need to do during the day on index cards and then do them) but you get out of the office for a while and there are juice boxes (well, hotel bars) afterwards. One day, for no apparent reason, Frank’s loving but exasperated wife Susan (Emily Mortimer) decides to have a little fun with him before a big lecture by setting the clock forward ten minutes so that he will be running earlier than usual. Alas, she isn’t that swift and sets them back ten minutes later and causes him to fall an hour behind schedule. This one little slip kicks off a chain of events that leads to Frank finding himself alone in a hotel room with a corporate hottie (Sarah Chalke), assisting a pregnant woman whom he saves after a car accident, getting thrown out of his house when Susan hears from the hospital about the baby and mistakenly assumes that Frank is the father and, while taking a paternity test to prove to her that the kid isn’t his, discovers that he has a genetic condition that proves not only that the baby in question can’t possibly be his, his young daughter (Matreya Fedor) isn’t his either.

Stunned by these revelations, Frank leaves his family and holes in up a motel and while sitting there feeling sorry for himself, he comes to the realization that his entire philosophy–that the world can be made into a tidy and orderly place–is nothing more than a hollow lie and that life is too chaotic to be controlled or tamed. He resolves to embrace this idea and vows to let every aspect of his life from then on to be governed by chance–he gets into barroom fights, he rides a motorcycle without a helmet and whenever a decision is to be made, he writes his options down on his index cards (no sense letting them go to waste) and picks one at random to follow, as though his entire existence were one elaborate Choose Your Own Adventure book. Meanwhile, Susan has finally figured out what has set him off and desperately tries to track him down in order to get him to come back to his family. At the same time, his bounder best friend (Stuart Townsend), who turns out to be the real father of Frank’s daughter (the result of a pre-marital fling between him and Susan), is torn between trying to get everything back to the way it was and a desire to reject his rascally ways and become a real father to the daughter he never knew he had.

With its basic premise of an upper-middle-class man who suddenly rejects all the aspects of his drab and dull suburban existence in order to discover who he really is, there will probably be some people out there who will try to compare “Chaos Theory” to “American Beauty.” Actually, “Chaos Theory” is more like what “American Beauty” felt like the second time you saw when its virtues (the Kevin Spacey performance and some of the spiky dialogue) faded away and its considerable flaws (such as the horribly cliched and decidedly one-note characters and the hollowly manipulative and borderline sexist screenplay) began to dominate the proceedings. The good thing about “Chaos Theory” is that it saves viewers some time by revealing its considerable flaws the first time out, thereby forgoing the need for second viewing. The elaborate hoops that screenwriter Daniel Taplitz jumps through in order to set up his premise are too absurd to be believed (all the stuff involving the pregnant woman is ridiculous, especially the unlikely manner in which it resolves itself) and when Frank finally has his breakthrough, it basically turns him from one kind of an asshole (a stick-in-the-mud yutz) into just another kind of asshole (the kind of obnoxious boor who loves to prattle on and on about how free he is). Meanwhile, the supporting characters are never believable for a second–we never understand why Susan would be so quick to assume the worst about Frank or why the best pal would suddenly want to become a family man type except that in both cases, the screenplay has nowhere to go if they don’t–and the mechanics that are employed to bring them together in the end at a remote cabin by the lake and resolve all their problems in a tear-jerking conclusion are so contrived that even those viewers who have been with the film up to this point are likely to throw up their hand in frustration. Oh yeah, I almost forgot–the main story is actually framed as a flashback being recounted by an older, wiser Frank to his future son-in-law when he seems to be getting a case of pre-wedding jitters, a narrative choice that adds nothing of value to the proceedings.

To give “Chaos Theory” a little bit of credit, I will say that while Ryan Reynolds has been given a badly written and virtually unplayable role, his efforts are credible enough to suggest that there may be a decent actor lurking behind the walking smirk that appeared in the likes of “Van Wilder” and that “Waiting” monstrosity. In addition, I liked the brief supporting turn from Sarah Chalke as his chief temptress–she isn’t on the screen very much but when she does, she injects the proceedings with the kind of energy and humor that it is otherwise lacking. Beyond that, “Chaos Theory” is an obnoxious and uninteresting film in which obnoxious and uninteresting people do obnoxious and uninteresting things for 90-odd minutes before arriving at an unearned and undeserved happy ending. Then again, the only ending that I can think of that these characters deserve would be to have the guys from “Funny Games” arrive at the cabin to inquire about the availability of some eggs.